Treatment Options for Hyperthyroidism in Cats

Hyperthyroidism, a condition that is defined as an overactive thyroid gland, is one of the most common health conditions to affect senior cats. Left untreated, hyperthyroidism will adversely affect your cat’s blood pressure and kidney health, and it can result in congestive heart failure. If your cat has been diagnosed with hyperthyroidism, there are several options to consider when it comes to treating your cat’s condition.

Drug Management

One treatment option for cats with hyperthyroidism is the administration of methimazole, which lowers the amount of thyroid hormone produced by your cat’s thyroid gland. This medication must be administered to your cat for the remainder of its life. Methimazole is usually prescribed as an oral tablet. For those whose cats are less than cooperative for pilling, veterinary compounding pharmacies can formulate methimazole as a transdermal gel that gets applied topically to the inside surface of the cat’s outer ear.

One of the appeals of treating a cat with methimazole is that many owners prefer the idea of simply medicating their cat as opposed to putting their cat through other treatment options that can be stressful or invasive. Many owners also believe that the medication route is more economical. However, since the cat will require the medication for life and require periodic blood testing to ensure that the prescribed dosage remains effective, this option may not prove less costly in the long run. Bringing the cat to the veterinary clinic for these blood tests and having to adjust the dose to maintain an ideal level of thyroid hormone is one of the cons of methimazole treatment. Another con is that methimazole is not without potential side effects, which may include vomiting, lethargy and a decrease in appetite.

Dietary Management

Iodine plays an essential role in thyroid hormone production, and your cat gets iodine from its food. Prescription diets that are low in iodine help to reduce the level of thyroid hormone produced. These diets are available only from your veterinarian, who may prescribe the dietary management alone or to supplement the use of methimazole so that a lower dose of the medication may be needed. Hills Prescription Diet y/d is available in canned and dry variations, and it is formulated to also support renal health and heart health.

Surgical Thyroidectomy

Surgical removal of the diseased portion of your cat’s thyroid gland is another option for treating hyperthyroidism. The pro to the surgical option is that if the correct portion of the thyroid gland is removed, the cat will be able to maintain a normal level of thyroid hormones without the need for medication. There are several cons to this surgery, however. If too much of the thyroid gland is removed, the cat will not produce enough thyroid hormone. This opposite condition is called hypothyroidism, and thyroid hormone medication will be required for the life of the cat. If an insufficient amount of the thyroid gland is removed, the cat will continue to have hyperthyroidism. Additionally, the general risks of surgery and anesthesia must be considered in an older cat that may already have sustained kidney disease or a heart condition.

Radioiodine Treatment

Radioiodine treatment is the most effective treatment available for hyperthyroidism in cats, making the favorable outcome one of the pros of this option. The treatment involves a single injection of radioactive iodine-131. The procedure requires no anesthesia. No healthy surrounding tissue is destroyed, and no organs are damaged. There are no dangerous side effects associated with radioiodine treatment. Prior to radioiodine treatment, your cat will require a series of diagnostic tests, including blood tests, a urinalysis, radiographs and ultrasounds, to ensure that your cat is healthy enough to safely undergo and process the treatment. When it comes to the expense, radioactive iodine treatment is cost effective when compared to the costs associated with lifelong medication and blood screenings. There are only two potential cons of radioiodine treatment. It is only performed in some veterinary specialty centers since radioactive substances are handled, which can mean that owners residing in rural areas may have to commute for a sizable distance to access the nearest center. Secondly, the cat must spend an average of one to two weeks at the facility so that all traces of the radioactive material have dissipated from your cat’s system and the cat is deemed safe to return home to human family members. This stay can be stressful for some cats. If these cons are not insurmountable obstacle for you and your cat, and if your cat is a candidate for radioiodine treatment, pursuing this option is worthwhile. Most cats that undergo this simple treatment require no medications or additional treatment after that, and thyroid hormone level typically normalizes within a month.

Discuss the options with your veterinarian to determine which treatment is best for your cat. If your cat is a potential candidate for radioiodine treatment, your veterinarian will refer you to a specialty center for a consultation. Whichever option you choose, treating your cat’s hyperthyroidism is imperative in extending its lifespan and quality of life.

Consult with your veterinarian for medical advice before starting any treatment.
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